Synthesis, Characterization and Antimicrobial Studies of Schiff Base Derived from the Reaction of 2-Thiophenecarboxaldehyde and Ethylenediamine and its Metal (II) Complexes

Abstract

Schiff base was derived by condensation of 2-thiophenecarboxaldehyde and ethylenediamine. Its Mn(II), Fe(II) and Co(II) complexes have been prepared and characterized on the basis of melting point/decomposition temperature, solubility, molar conductance, magnetic susceptibility, elemental analysis, infrared spectroscopic analysis and UV-visible spectrophotometry. The Schiff base and complexes were found to be soluble in DMSO, DMF and some organic solvents thus, they are non-ionic compounds. The Decomposition temperatures of the complexes were found to be within the range of 173-246°C, showing the stability of the complexes. All the complexes have low molar conductance values (8.66-25.29 Ω⁻¹ cm2 mol⁻¹) indicating their non- electrolytic nature. Magnetic moment values of the complexes were found to be within the range of 3.847BM - 5.12BM which indicated that they are paramagnetic. Infrared spectra of the Schiff base indicated the azomethine peak at 1629cm-1 which shifted to the lower frequencies (1603-1562cm^-1) in the spectra of the complexes. Both analytical and spectroscopic data showed that the complexes were formed and the coordination sites were through the nitrogen of the azomethine (-HC=N-) group and the sulfur atom of the thiophene ring. 1:1 metal-ligand ratio was suggested The Schiff base and its complexes have been screened for their in vitro antimicrobial activity against three pathogenic bacteria (Staphylococcus aureus, Streptococcus pneumonia and Escherichia coli) and two pathogenic fungi (Aspergillus niger and Aspergillus flavus). The Schiff base shows moderate inhibition zone (06 - 14) whereas some of the metal chelates show slightly higher inhibition zone (06 - 17) mm against the bacteria and fungi but lower than that of the control drugs used (18-30) mm.